Blowing device for a laser system

ABSTRACT

The invention relates to a blowing device ( 4 ) for a laser system ( 1 ) used for separating or welding workpieces ( 17 ). The blowing device ( 4 ) has at least one nozzle assembly ( 5 ), which generates a gas stream ( 7 ) that is oriented at an angle to the laser beam ( 3 ). The blowing device also has an air supply ( 8 ) which, on one side of the nozzle, leads into the proximity of the nozzle opening ( 6 ) and which is provided for an air supply stream ( 10 ) that is fed to the gas stream ( 7 ) in an essentially parallel manner or at an apex angle. A second air supply ( 9 ) is arranged on the other side of the nozzle. Said second air supply leads into the proximity of the nozzle opening ( 6 ) and is provided for a second air supply stream ( 11 ) that is fed to the gas steam ( 7 ) in an essentially parallel manner or at an apex angle. A protecting glass ( 13 ), which is oriented toward the gas stream ( 7 ) in an essentially parallel manner, can be alternatively or additionally placed in the proximity of the nozzle opening ( 6 ). Said protecting glass is provided in the form of a pane and directly abuts against the nozzle opening ( 6 ) in a sealed manner. In the preferred embodiment, the outer cross-section of the nozzle ( 5 ) is provided in the shape of a drop or a vane, whereby at least the outer surfaces thereof extending toward the nozzle opening ( 6 ) form air conducting surfaces ( 12 ).

The present invention pertains to a blowing device for a laser meanswith the features described in the preamble of the principal claim.

Such a blowing device has been known from practice. It may be associatedwith a laser welding means or a laser cutting means by means of asuitable bracket. The blowing device has an elongated nozzle, which isdirected at right angles to the laser beam and generates a gas flowpassing through the laser beam. On the underside, the nozzle has an airfeed, which opens in the vicinity of the nozzle opening and via which anincoming air flow can be fed to the gas flow at an acute angle. Thehousing of the laser head joins on the other side of the nozzle.

Thus, an incoming air flow guided essentially in parallel is generatedunder the gas flow in the prior-art blowing device. An air curtain,which is to protect the laser optical system from contamination ordamage by spatters flying up from the melt, shall be formed by the twoflows. The prior-art arrangement has the drawback that, on the one hand,it is arranged at a great distance from the welding or cutting site, asa result of which the gas and air flows must cover and protect arelatively large cross section. This requires a very high kinetic flowenergy, which can be accomplished only insufficiently because of thediffusor effect and the pressure limited to a maximum of about 2.5 bar.On the other hand, the two flows are not yet sufficiently stable toguarantee an optimal protection from spatters. Furthermore, there arenoise problems and there is an unfavorable space requirement.

Another blowing device has been known from DE-A 44 35 531. A gas flow isguided here along a deflecting mirror in the laser optical system. Thisrequires a corresponding design of the laser means. The gas flow alsomust be curved.

Another blowing device shown in WO 95/03911, which provide closedchannel for the gas flow and has a correspondingly complicated design.As a result, the blowing device considerably reduces the freedoms ofdesign and the fields of use of the laser means.

The object of the present invention is to show a better blowing device.

This object is accomplished by the present invention with the featuresdescribed in the principal claim.

In the blowing device according to the present invention, the gas flowgenerated by the nozzle arrangement is enclosed and guided on bothsides, as a result of which swirling and consequently flow losses areextensively avoided. The kinetic energy and the blowing-away force ofthe gas flow are preserved, and the outflow pressure, which is limitedfor physical reasons, is optimally utilized.

The guiding of the gas flow can be accomplished either by two incomingair flows converging at an acute angle or essentially in parallel or bysuch an incoming air flow and a parallel protective glass. This flowguiding also minimizes the noises. The blowing device has asubstantially simpler design and is less expensive than prior-artembodiments. In addition, it may be positioned at any suitable point andit does not have an adverse effect on a possibly existing protective gasfeed for the welding process.

In the preferred embodiment, the nozzle is arranged at an open nozzleholder and may also be fastened in a height-adjustable manner. Thismakes possible the lateral feed of incoming air from the environment andan outside flow around the nozzle, which is also especially advantageousfor the flow guiding in conjunction with the drop or wing shape, whichis favorable for flow. In addition, the gas and air flow may be placedat a favorable level, at which the scattering or cone cross section isrelatively small for protection against spatters, and the existingkinetic energy of the air flow is sufficiently strong for blowing awayeven larger spatters. In addition, the other components of the lasermeans are not affected adversely due to the open design and arrangementof the blowing device.

Additional advantageous embodiments of the present invention aredescribed in the subclaims.

The present invention is schematically represented in the drawings as anexample. Specifically,

FIG. 1 shows a side view of a laser means with a blowing device,

FIG. 2 shows a tilted side view of the arrangements according to FIG. 1corresponding to arrow II,

FIG. 3 shows a top view of the arrangement in FIG. 1 according to arrowIII, and

FIGS. 4 and 5 show variants of the nozzle arrangement according to FIGS.1 through 3 with a protective glass.

FIGS. 1 and 2 show in two side views a laser means (1), which is used toweld or cut workpieces (17) shown schematically by means of a laser beamor a bundle of laser beams (3). For clarity's sake, only the laser head(2) and the beam (3) of the laser means (1) are shown. A blowing device(4), which generates a gas flow (7), which is directed essentially atright angles to the laser beam (3) and protects the laser optical systemarranged above it from contamination or damage due to weld spattersflying up, smoke or other effects from the welding or cutting process,is arranged at the laser means (1).

The blowing device (4) preferably has at least one nozzle (5), which isdesigned as a transversely directed nozzle bar and has a longitudinallydirected, laterally slot-like nozzle opening (6) for discharging the gasflow (7). Opposite compressed air connections (15), of which only one isshown in FIG. 2, are arranged at the two front ends of the nozzle (5).The compressed air connections (15) on both sides press the gas axiallyinto the hollow interior space of the nozzle (5) with inflow directionsdirected against one another. As a result blow-off pressure that isextensively constant over the slot length of the nozzle opening (6) isobtained. As an alternative, the compressed air connection may belocated only on one front side or in the rear. The gas (7) may be air orany other gas.

The nozzle (5) preferably has a drop-shaped or wing-shaped cross sectionand is fastened at the laser head (2) at a selectable level by means ofan open nozzle holder (14). The nozzle holder (14) has for this purpose,e.g., a window (16) shown in FIG. 2, which makes possible the entry ofoutside air to the outer surfaces of the nozzle (5), which are locatedat the top. The nozzle (5) may be held extensively freely floating andmay be flown past by the ambient air on the rear side as well as on theunderside and the top side, The nozzle holder (14) may have aheight-adjustable design or be fasted to the laser head (2) in aheight-adjustable manner.

In the embodiment shown in FIGS. 1 through 3, the trapezoidal nozzle (5)has on the outer side two outer walls, which extend obliquely to thenozzle opening (6) and open there and are used for bilateral air feed(8, 9) and for incoming air flows (10, 11) flowing past on both sides.The incoming air flows (10, 11) are drawn in from the ambient outsideair by the gas flow (7) being discharged from the nozzle opening (6)under a high pressure of about 2.5 bar.

The incoming air flows (10, 11) reach the nozzle opening (6) at an acuteangle and are deflected there in parallel to the gas flow (7). As aresult, the two incoming air flows (10, 11) embed the gas flow (7)between them and guide it on both sides. On the whole, this results in athree-layer, essentially laminar flow, which has an especially high flowstability while swirling is extensively avoided. The kinetic energy ofthe flows is preserved over a rather great length of flow, so that thethree-layer flow has sufficient force to blow away ascending spatters,smoke or the like in front of the laser head (2) and the laser opticalsystem arranged there.

FIGS. 4 and 5 show two variants of the embodiment according to FIGS. 1through 3. In the embodiment according to FIG. 4, only the incoming airflow (10) is present on the underside of the nozzle (5). Instead of theupper incoming air flow (11), a preferably a flat pane-shaped protectiveglass (13), which is transparent to the laser beam, is located above thegas flow (7), and this protective glass extends in parallel to the saidgas flow and it sealingly joins with its edge the nozzle opening (6). Asa result, the inflow of the incoming air flow is prevented on this side.The protective glass (13) is fastened in the laser head (2) or at thenozzle holder (14) in a suitable manner. It forms, instead of the upperincoming air flow (11), the upper parallel guide for the gas flow (7),which is embedded and guided as a result between the protective glasspane (13) and the lower incoming air flow (10). The protective glass(13) additionally protects the laser optical system against spatters. Itis preferably arranged detachably and can be replaced when necessary.

The same incoming air flows (10, 11) converging conically on both sidestoward the nozzle opening (6) are again present in the variant accordingto FIG. 5 as in FIGS. 1 through 3, and a protective glass (13), which ispositioned in the laser head or in the nozzle holder (14) at a spacedlocation above the nozzle opening (6), is additionally arranged. Theprotective glass (13) has no guiding function for the gas flow (7) inthis case and is used above all as an additional mechanical protectionagainst spatters.

Various modifications of the embodiment shown are possible. On the onehand, the outer shape of the nozzle (5) may be different. The air feeds(8, 9) may also be designed as jacketed flow channels instead of as openguide surfaces (12). Furthermore, two or more nozzles (5) may bepresent.

LIST OF REFERENCE NUMBERS

1 Laser device

2 laser head

3 laser beam

4 blowing device

5 nozzle, nozzle arrangement

6 nozzle opening, slotted nozzle

7 gas flow

8 air feed

9 air feed

10 incoming air flow, outside air

11 incoming air flow, outside air

12 air guide surface

13 protective glass, protective glass pane

14 nozzle holder

15 compressed air connection

16 window

17 workpiece

What is claimed is:
 1. A blowing device with a nozzle holder formounting on a laser system providing a laser beam, for cutting orwelding workpieces, the blowing device comprising: at least one nozzlearrangement which generates a gas flow directed at an angle to the laserbeam, the nozzle arrangement having a nozzle opening; an air feedopening on one side of the nozzle, in the vicinity of said nozzleopening, said air feed opening for an incoming air flow fed inessentially in parallel or at an acute angle to said gas flow; one of aprotective glass directed essentially in parallel to the gas flow and asecond air feed opening in the vicinity of the nozzle opening arrangedon the other side of the nozzle, said second air feed opening for asecond incoming air flow fed in essentially in parallel or at an acuteangle to the said gas flow.
 2. A blowing device in accordance with claim1, wherein said protective glass has a pane-shaped design and isarranged directly adjoining said nozzle opening and in a sealing manner.3. A blowing device in accordance with claim 1, wherein said nozzle hasa drop-shaped or wing-shaped cross section on an outside and has outersurfaces extending toward said nozzle opening to form air guidesurfaces.
 4. A blowing device in accordance with claim 1, wherein saidnozzle is arranged at an open nozzle holder and outside air can flowaround said nozzle on both sides.
 5. A blowing device in accordance withclaim 1, wherein said nozzle is arranged at said nozzle holder in aheight-adjustable manner.
 6. A blowing device in accordance with claim1, wherein said nozzle is designed as a nozzle bar and has two oppositecompressed air connections on front sides.
 7. A blowing device,comprising: a nozzle holder for mounting on a laser system providing alaser beam, for cutting or welding workpieces; at least one nozzlearrangement connected to said nozzle holder, said nozzle arrangementgenerating a gas flow directed at an angle to the laser beam, the nozzlearrangement having a nozzle opening; an air feed opening on one side ofthe nozzle, in the vicinity of said nozzle opening, said air feedopening for an incoming air flow fed in essentially in parallel or at anacute angle to said gas flow; another protection feature on the otherside of the nozzle, the another protection feature being one or more ofa protective glass directed essentially in parallel to the gas flow anda second air feed opening in the vicinity of the nozzle opening arrangedon the other side of the nozzle, said second air feed opening for asecond incoming air flow fed in essentially in parallel or at an acuteangle to the said gas flow.
 8. A blowing device in accordance with claim7, wherein said protective glass has a pane-shaped design and isarranged directly adjoining said nozzle opening and in a sealing manner.9. A blowing device in accordance with claim 7, wherein said nozzle hasa drop-shaped or wing-shaped cross section on an outside and has outersurfaces extending toward said nozzle opening to form air guidesurfaces.
 10. A blowing device in accordance with claim 7, wherein saidnozzle is arranged at said nozzle holder, which is open, and outside aircan flow around said nozzle on both sides.
 11. A blowing device inaccordance with claim 7, wherein said nozzle is arranged at said nozzleholder in a height-adjustable manner.
 12. A blowing device in accordancewith claim 7, wherein said nozzle is designed as a nozzle bar and hastwo opposite compressed air connections on front sides.
 13. A blowingdevice in accordance with claim 7, wherein said protective glass isarranged spaced from said nozzle opening with said second air feedopening between said nozzle opening and said protective glass.